The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 16-50mm F2.8 SSM and the Sigma 18-50mm F2.8-4.5 DC OS HSM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 18-50mm F2.8-4.5 DC OS HSM is the longer of the two lenses at 89mm. The Sony DT 16-50mm F2.8 SSM with a length of 88mm is 1mm shorter. On the other hand, the Sony DT 16-50mm F2.8 SSM has a larger diameter of 81mm compared to Sigma 18-50mm F2.8-4.5 DC OS HSM's 74mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sigma 18-50mm F2.8-4.5 DC OS HSM weighs 395g, 31% (182g) lighter than the Sony DT 16-50mm F2.8 SSM's weight of 577g.
Below you can find the dimension and weight table of the 'Standard Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Standard Zoom Lenses in Sony Alpha Mount for Size Comparison
Lens Mounts
Both Sony DT 16-50mm F2.8 SSM and Sigma 18-50mm F2.8-4.5 DC OS HSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Sigma 18-50mm F2.8-4.5 DC OS HSM is also available in Canon EF , Pentax KAF3, Sigma SA and Nikon F (DX) mounts.
Focal Range
Sony DT 16-50mm F2.8 SSM has a focal range of 16-50mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 24-75mm when used on a APS-C / DX format camera. Sigma 18-50mm F2.8-4.5 DC OS HSM has a focal range of 18-50mm and 2.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-75mm when used on a APS-C / DX format camera.